This invention relates to wire tensioners, and particularly to tensioners used to regulate wire tension during the process of winding coils for electrical components such as electric motor armatures and stators.
The process of manufacturing armatures, stators, and similar electric motor parts involves several wire winding steps, including coiling wire around a workpiece and forming connections to lead terminations such as the commutator of an armature. A typical armature winder, for example, dispenses wire from a flyer that rotates around a stationary armature. During the winding process, it is important to keep the tension of wire leaving the flyer fairly high in order to create a sufficiently compact and orderly coil about the armature and to ensure the correct attachment of the wire to various types of commutator connections. However, wire tension can vary sharply during winding due to accelerations and decelerations of the flyer, particularly between process steps, when the flyer changes its direction of rotation and when winding at high speeds. This can result in a wire break unless a wire tensioner is used to maintain the wire at a constant tension.
Typically, wire tensioners regulate tension using either a spring and pulley arrangement or a source of variable drag to apply tension to the wire being wound. With the spring arrangement, when wire tension rises, excess tension is absorbed by stretching the spring. When tension drops, pressure from the spring or additional drag from the variable drag element maintains the wire sufficiently taut.
The performance of winding machines is enhanced by the incorporation of wire tensioners, as a more stable wire tension allows machines to be operated at higher speeds without risking wire breaks due to tension transients. Nevertheless, the degree of tension control supplied by previously known wire tensioners has generally not been sufficient for all winding applications. It would thus be desirable to be able to provide an improved wire tensioner that is capable of generating faster and stronger corrective tensions than previously possible so that winding machine performance may be increased.